Rain sensors and light sensors are incorporated already into many vehicles today in order to control the actuation of windshield wipers or vehicle lights. As more and more vehicles have cameras integrated as a basis for assistance or comfort functions, rain or light detection is also increasingly performed using a camera.
In WO 2010/072198 A1 rain detection is described which uses a camera that at the same time is also used for automotive driver assistance functions. A bifocal optic is used for rain detection, producing a sharp image of a partial region of the windshield on a partial region of the camera image sensor.
EP 2057583 B1 shows a camera-based driver assistance function for the automatic light control of headlamps, which distinguishes the vehicle lights of vehicles ahead or oncoming vehicles from reflectors. The headlamps of one's own vehicle can thus be controlled automatically such that blinding of the drivers of vehicles travelling ahead or of oncoming vehicles is prevented.
The range and distribution of the illumination provided by the headlamps can be adjusted accordingly to vehicles ahead and oncoming vehicles.
Difficulties arise with camera-based driver assistance functions due to environmental effects such as rain or darkness at night, which can considerably affect the imaging quality of the camera.